chore: use matrix on all available OSes and different go versions

Signed-off-by: Keith Zantow <kzantow@gmail.com>

.github/workflows/build.yml

@@ -2,29 +2,22 @@
 
 name: build
 on: [push, pull_request]
-env:
-  go-version: '1.18'
 jobs:
   tests:
-    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        go-version: ['1.18', 'stable']
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
         with:
-          go-version: ${{ env.go-version }}
+          go-version: ${{ matrix.go-version }}
       - name: Run tests
         run: make test
       - name: Send coverage report to coveralls
         uses: shogo82148/actions-goveralls@v1
+        if: ${{ matrix.os == 'ubuntu-latest' && matrix.go-version == 'stable' }}
         with:
           path-to-profile: profile.cov
-
-  windows-tests:
-    runs-on: windows-2022
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-go@v5
-        with:
-          go-version: ${{ env.go-version }}
-      - name: Run tests
-        run: make test